Poly-2-pyrrolidone is produced by the alkaline-catalyzed polymerization of 2-pyrrolidone. The catalyst system may comprise a partially carbonated pyrrolidonate salt made, for example, by reacting an alkali metal hydroxide with 2-pyrrolidone, or by reacting a quaternary ammonium hydroxide with 2-pyrrolidone, dehydrating, and contacting the product with carbon dioxide (U.S. Pat. No. 3,721,652). Japanese Pat. No. 47-26195 discloses a process for making a catalyst by reacting a non-water-forming alkali metal compound with 2-pyrrolidone and contacting the product with a quaternary ammonium halide under anhydrous conditions. In U.S. Pat. No. 3,835,100, the catalyst obtained by reacting an alkali metal alkoxide with a quaternary ammonium halide and contacting the product, ammonium alkoxide, with 2-pyrrolidone, also avoids the production of water. While both of the latter processes are anhydrous, they do not produce poly-2-pyrrolidone and very high molecular weight in ordinary reaction times. For many purposes, it is advantageous to be able to rapidly produce poly-2-pyrrolidone having high molecular weight, e.g. in excess of 500,000, in good yield.